Nitrogen oxide decomposing element and nitrogen oxide decomposing apparatus including the same

Abstract

A nitrogen oxide decomposing element and a nitrogen oxide decomposing apparatus can perform a treatment at a relatively low temperature without using a material, which is suspected to have influence on the environment and human body, as an oxidant or a catalyst. There is proposed a nitrogen oxide decomposing element 1 including a conductive solid electrolyte film 2 for selectively allowing a hydrogen ion to pass through, a first electrode layer 3 made of an electronic conductivity base material and a catalyst for accelerating anodic oxidation, a second electrode layer 4 made of an electronic conductivity basematerialandacatalystforacceleratingcathodicreduction, and a platinum group catalyst 6 supported by a porous metal oxide 5 disposed to be adjacent to the second electrode layer 4. A low-power consumption nitrogen oxide decomposing apparatus which can efficiently use electric energy is obtained by locating a nitrogen oxide sensor 14 in the vicinity of the platinum group catalyst 6 supported by the metal oxide 5, and controlling the magnitude of a current flowing between the first and the second electrode layers 3 and 4 and the energization time by a power source/control device 15 in accordance with the concentration of nitrogen oxide detected by the nitrogen oxide sensor 14.

1 - 12 . (canceled)  
   
   
       13 . A nitrogen oxide decomposing element, comprising: a conductive solid electrolyte film for selectively allowing a hydrogen ion to pass through; a first electrode made of an electronic conductivity base material disposed on a part of a surface of the conductive solid electrolyte film and a catalyst for accelerating anodic oxidation; 
 a second electrode made of an electronic conductivity base material disposed on the other part of the surface of the conductive solid electrolyte film and a catalyst for accelerating cathodic reduction; and    a platinum group catalyst supported by a porous metal oxide disposed to be adjacent to the second electrode.    
   
   
       14 . The nitrogen oxide decomposing element according to  claim 13 , wherein the first and the second electrodes are respectively provided on opposed plane surfaces of the surface of the conductive solid electrolyte film.  
   
   
       15 . The nitrogen oxide decomposing element according to  claim 13 , wherein the first and the second electrodes are provided on a same plane surface of the surface of the conductive solid electrolyte film.  
   
   
       16 . The nitrogen oxide decomposing element according to  claim 13 , wherein a mixed layer including an electronic conductivity base material, a solid electrolyte film, a platinum group catalyst and a cathodic catalyst is provided between the conductive solid electrolyte film and the second electrode.  
   
   
       17 . The nitrogen oxide decomposing element according to  claim 13 , wherein the metal oxide is an acidic oxide.  
   
   
       18 . The nitrogen oxide decomposing element according to  claim 17 , wherein the metal oxide includes at least one component of titanium dioxide, zirconium dioxide, aluminum oxide, silicon oxide, magnesium oxide, and tin oxide.  
   
   
       19 . The nitrogen oxide decomposing element according to  claim 13 , wherein the metal oxide is an amphoteric oxide.  
   
   
       20 . The nitrogen oxide decomposing element according to  claim 19 , wherein the metal oxide includes at least one component of titanium dioxide, zirconium dioxide, aluminum oxide, silicon oxide, magnesium oxide, and tin oxide.  
   
   
       21 . The nitrogen oxide decomposing element according to  claim 13 , wherein the platinum group catalyst includes at least one component of platinum, iridium, and palladium.  
   
   
       22 . A nitrogen oxide decomposing apparatus, comprising: 
 the nitrogen oxide decomposing element according to any one of  claims 13  to  21  and a frame holding this; a gas supply ports for supplying an anode gas and a cathode gas into the frame; a gas exhaust port for exhausting the gases in the frame to outside; and a power source for applying a DC voltage between the first and the second electrodes.    
   
   
       23 . The nitrogen oxide decomposing apparatus according to  claim 22 , wherein a gas containing water vapor is supplied as the anode gas.  
   
   
       24 . The nitrogen oxide decomposing apparatus according to  claim 22 , wherein a gas containing nitrogen oxide is supplied as the cathode gas.  
   
   
       25 . The nitrogen oxide decomposing apparatus according to  claim 22 , wherein the nitrogen oxide decomposing apparatus further comprises a sensor for detecting a concentration of nitrogen oxide, and a control device for controlling a magnitude of a current flowing between the first and the second electrodes and an energization time in accordance with the concentration of the nitrogen oxide detected by the sensor.  
   
   
       26 . The nitrogen oxide decomposing apparatus according to  claim 25 , wherein the sensor is located in a vicinity of the platinum group catalyst supported by the metal oxide.